This invention relates to an apparatus for obtaining undisturbed soil cores. Soil cores with undisturbed structure are desirable to measure physical and chemical properties, particularly water content and nutrient movement.
Undisturbed soil sampling techniques using hand-driven equipment were reported by Lutz, Soil Sci. 64: 399-401, 1947; and Veihmeyer, Soil Sci. 27: 147-152, 1929. The machine built by Kelley et al., Soil Sci. Soc. Amer. Proc. 12: 85-87, 1947, could take undisturbed soil cores of 5- and 10-cm. (2- and 4-in.) diameters and up to 1.8 m. (6 ft.) long. An earlier machine reported by Kelley and Haise, J. Amer. Soc. Agron. 39: 828-830, 1947, had similar sampling capabilities but required a considerable amount of manual labor. Hydraulic and electric units developed to increase sampling speed have been developed by Jensen et al., Trans. Amer. Soc. Agr. Eng. 3(1): 22-24, 1960; and Buchele, Trans. Amer. Soc. Agr. Eng. 4(2): 185-187, 1961.
Kelley et al. (supra) reported using a split-sheet metal container to protect the soil sample from fracture during transport to the laboratory. Care in sample handling and processing is required for all undisturbed samples. Split-tube-type samplers require that the sample be removed, trimmed, and coated with a casing material. Adsorption of paint-on, or dip-type coating materials, may affect the effective cross-section of the core and provide little mechanical support. Rigid wall sample containers may permit undetected water flow paths which would affect results and conclusions.
Bondurant et al., Soil Sci. 107: 70-71, 1969, used heat-shrinkable tubing (polyolefin) to encase undisturbed soil cores. The space between the soil core and the outer barrier was effectively sealed on soil cores 240 mm. long and 82 mm. diameter.
In accordance with the invention, I have discovered, in an apparatus for collecting undisturbed soil core samples of the type comprising a cylindrical tube or sample body, open at both ends, and having at one end thereof a cutting tip which is sharpened to facilitate entry into the ground, an improvement comprising a tubular lining of flexible heat-shrinkable plastic open at both ends, contained within said sampler body, and having an outside diameter which is essentially equal to the inside diameter of said sampler body; and a means for securely holding said tubular lining in place.
This heat-shrinkable, plastic-lined soil core sampler is then pressed into the ground, removed from the ground, and the plastic lining heated to a temperature sufficient to cause shrinkage of the plastic to the soil.
The drawings consist of a perspective view and two section views of the sampler body, and two perspective views of retaining rings.